- Long battery life (for wandering around all day with it)
Mine only lasts about 2-2.5 hours I think. Unless you're one of those people who insist on playing games during lectures, that shouldn't be a problem.
But why not let your friend's son set the requirements? He is the one who is going to use it, and if he is going to study computer science it's likely he already knows stuff about computers and has an opinion on all the Windows/OS X/Linux stuff.
If it's purely for doing undergraduate CS things, you could probably get by with 1 GB of RAM, 80 GB disk space, on-board graphics card and low-end CPU. Any Linux distro would do fine with that, and if you choose a minimal window manager like xmonad you won't use a lot memory and GPU power on that.
Of course if he wants to do more than just that, there is no way that computer would be adequate.
Also note that computing power and battery life is often inversely proportional.
Bottom line: Ask him for his requirements, not us.